If you run a blog that has ever allowed comments then you are probably well aware of Comment Spam. Comment Spam is when a blog gets inundated with comments to posts that add no benefit to the post. As a novice blogger you are often tempted to accept any flattering comments about your blog and so authorise comments from any source. This can lead to your blog becoming populated with often meaningless comments that do not make sense when taken in context with the original post. The type of comment I mean would be something along the lines of “Hey, thanks for a really informative post. I’ve been researching this subject a lot recently and will definitely bookmark your site”. This in response to a post about how I wish dog owners would clean up after their dogs! Comment spam is not something you particularly want on your blog. It degrades the quality of your post and makes readers less likely to want to join your community. Genuine commenters may be put off responding to one of your posts if they think that their relevant reply will be drowned out amidst a sea of spam offering a variety of unrelated and often undesirable services.

You might wonder why anybody would want to post these inane comments. The simple reason is search engine optimisation. The spammer is often trying to create a link from your site to the one that they are promoting. Now before you start feeling smug that the spammer regards your site as being so popular that you will generate a lot of traffic for him, that’s not the reason he wants a link to your site. Google regards a link into a website as a vote of confidence in the site from the linking site. A vote of confidence in a site suggests that the site is providing high quality content. Lots of inbound links to a website suggests a lot of people think the site is providing high quality content. However as well as knowing that a website provides high quality content Google also needs to know what that high quality content is about. To do this Google looks at the text that contains the link. This is called the anchor text. Google takes this text to be a signal of the content that will be found at the destination of the link. If the anchor text says “SEO Specialist Blackburn” then Google will increase the ranking of the destination website for that search term.

So now you know why blog spammers do what they do how can you stop them? There are a number of methods that you can use. Some of them are technological such as disallowing links in posts. Spammers often use the post itself to include a link to the site they wish to promote, if they cannot get their inbound link there is no point in them posting.

Spammers are ingenious though and use another method to get their link into your post, they use the name and website address of the poster to slip in their nefarious link. The spammer may post as “Low Priced Widgets” and include the site they are promoting. This will then display as the author of the comment “Low Priced Widget” and when you click on their name you will be taken to their website. To counteract this you can use the “nofollow” attribute in your links. When Google spiders your site it will ignore any links that are “nofollow” and this will deprive the spammer of their SEO oxygen, inbound links.

You might want to try banning certain keywords. Phrases such as online casino and Viagra are often popular sources of comment spam. Although this can be easily got round by the spammer posing “c@sino” or “Vi@gra” there is little benefit for the spammer as they are really looking for an exact keyword match within their link.

There are less sophisticated but probably more effective methods that you could try. First of all when you read a comment ask yourself two questions :

1. Does this comment make sense in context with the post?
2. Would this comment make as much sense if it was a reply to a post on a blog about football, knitting or quantum physics?

If the answer to either of these questions is “Yes”, then it is probably spam and should be ignored.

Another method is to look at the name of the comment poster, if it is something like “Best Car Rental” rather than a persons name, again, I would ignore the comment.

By using just these last two methods you should be able to keep your blog pretty much free of comment spam which is good for you and your readers!